Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

This thread was archived. Please ask a new question if you need help.

Complex Firefox upgrade

Jose de la Mancha
Jose de la Mancha
more options

Hi everybody. Thanks in advance for your help.

I'm on Win 11 23H2, and I'm currently running Firefox 88.0.1 x64. Why? Because it's heavily customized to suit my needs. Some examples:

  • Extensions (e.g. Classic Theme Restorer)
  • userChrome.css and userContent.css customizations ( https://github.com/aris-t2/customcssforfx ), which include tabs on bottom (mandatory for me), tab height/width, and many other things.

I decided a long time ago to stay with v88 because every new Firefox update was breaking things that I needed, and I got tired to spend hours with every new update. If only Firefox devs could find a way to NOT break user customizations with every new update...

Of course I'd like to update my Firefox to the latest version. But I know that it's going to be a nuclear bomb. I already made a test. First I made a backup of my profile folder, then I just updated Firefox. Suffice to say that not only all my customizations disappeared : even my tabs disappeared, and I have dozens of them. So I had to uninstall everything, copy back my previously saved profile folder (because of course it had been modified by the latest version), and reinstall Firefox 88.0.1.

So here's my plan and my question. Would it be possible to have two different Firefox installs (not portable I guess), with two different profiles, running at the same time?

  • Here's how I see it:
  • Download Firefox latest version
  • Close Firefox 88
  • Move profile folder away from AppData\Roaming\Mozilla\Firefox\Profiles, so Firefox latest version can't find it
  • Move Firefox folder (the one within Program Files) so hopefully Firefox latest version can't find it
  • Install Firefox latest version (it then creates a new user profile folder)
  • Start Firefox latest version
  • Move back the old Firefox folder to Program Files (so there will be two different Firefox folders, e.g. "Mozilla Firefox 88" and "Mozilla Firefox")
  • Move back the old profile folder to AppData\Roaming\Mozilla\Firefox\Profiles (so there will be two different user profile folders)
  • Start Firefox 88

Would that work, or am I missing something?

If it worked, then I could keep working on Firefox 88, while gradually customizing Firefox latest version until it's ready to take over.

Thanks in advance for your insights!

Hi everybody. Thanks in advance for your help. I'm on Win 11 23H2, and I'm currently running Firefox 88.0.1 x64. Why? Because it's heavily customized to suit my needs. Some examples: * Extensions (e.g. Classic Theme Restorer) * userChrome.css and userContent.css customizations ( https://github.com/aris-t2/customcssforfx ), which include tabs on bottom (mandatory for me), tab height/width, and many other things. I decided a long time ago to stay with v88 because every new Firefox update was breaking things that I needed, and I got tired to spend hours with every new update. If only Firefox devs could find a way to NOT break user customizations with every new update... Of course I'd like to update my Firefox to the latest version. But I know that it's going to be a nuclear bomb. I already made a test. First I made a backup of my profile folder, then I just updated Firefox. Suffice to say that not only all my customizations disappeared : even my tabs disappeared, and I have dozens of them. So I had to uninstall everything, copy back my previously saved profile folder (because of course it had been modified by the latest version), and reinstall Firefox 88.0.1. So here's my plan and my question. Would it be possible to have two different Firefox installs (not portable I guess), with two different profiles, running at the same time? * Here's how I see it: * Download Firefox latest version * Close Firefox 88 * Move profile folder away from AppData\Roaming\Mozilla\Firefox\Profiles, so Firefox latest version can't find it * Move Firefox folder (the one within Program Files) so hopefully Firefox latest version can't find it * Install Firefox latest version (it then creates a new user profile folder) * Start Firefox latest version * Move back the old Firefox folder to Program Files (so there will be two different Firefox folders, e.g. "Mozilla Firefox 88" and "Mozilla Firefox") * Move back the old profile folder to AppData\Roaming\Mozilla\Firefox\Profiles (so there will be two different user profile folders) * Start Firefox 88 Would that work, or am I missing something? If it worked, then I could keep working on Firefox 88, while gradually customizing Firefox latest version until it's ready to take over. Thanks in advance for your insights!

All Replies (4)

cor-el
cor-el
  • Moderator
  • Top 10 Contributor
more options

Did you try to update Firefox via "Help -> About Firefox" instead of installing the current release as that is usually best to ensure that files get updated to new schemes?

Your userChrome.css will likely no longer be compatible and best is to start with a new file and get updates from their authors.

Jose de la Mancha
Jose de la Mancha Question owner
more options

Sorry, I wasn't clear. The update that I tried and which resulted in a catastrophe was indeed via "Help > About Firefox".

I'd like to know if my plan is feasible (two different Firefox installs with two different profiles, running at the same time) or if there are technical issues that I'm unaware of.

Thank you.

Modified by Jose de la Mancha

Agent virtuel
Agent virtuel
more options

Hello

Can I run two different versions of Firefox at the same time? https://support.mozilla.org/en-US/questions/1439349

Jose de la Mancha
Jose de la Mancha Question owner
more options

Is it really mandatory to create a "Mozilla Firefox Release" folder, named specifically that way? Like I said, maybe I just want to create these two folders: Old version: Program Files\Mozilla Firefox 88\ New version: Program Files\Mozilla Firefox\

Plus my biggest concern is the new version messing with my old version's profile folder. That's why my plan is to move the old profile folder away during Firefox (new version) installation, until Firefox (new version) has created its own profile folder, then move the old profile folder back so that Firefox 88 can keep finding it.